Unperforated slide-in passenger side airbag module cushion cover

Abstract: An automotive airbag module assembly including a trough shaped reaction canister (10) with first and second side walls (12,14) and a cover (46) for covering a mouth of the reaction canister (10). A locking spline (48) on the cover (46) is longitudinally engageable with a locking channel (38) in the first wall (12) and a latching spline (54) is engageable with a complementary latching channel (42) in the second wall (14) by a longitudinal sliding or snap-fit engagement. When the airbag (32) is deployed the latching spline (54) is forced from the latching channel (42) but the locking spline (48) is retained in the locking channel (38) retaining the cover (46) on the reaction canister (10).

Description: This invention relates to passenger side vehicular airbag modules. More particularly, it relates to an improved cushion cover for such a module. Most passenger side airbag modules employ cushion covers. The term "cushion" as used herein means the folded and undeployed airbag. The purposes of the cover are to prevent foreign objects from lodging inside the cushion and to retain the cushion fold until the module is installed in a vehicle and a deployment door is attached over it. Cushion covers presently employed may be made of plastic fiber papers such as Tyvek (a DuPont trademark), woven fabric, or injection molded or die cut sheet plastic. These prior art cushion covers are normally secured to the module by means of adhesive bonding, sewing, or fastening with screws or rivets. They are designed with perforated lines or tear seams which are designed to split when the airbag deploys. The cover portions then swing open allowing full deployment of the airbag. The prior art cushion covers have a number of disadvantages. First, as previously explained, they require the use of fasteners or adhesives, thereby complicating the task of assembly. Second, the presence of a perforation or tear line invites inadvertent splits due to handling prior to or during installation. Finally, the presence of two relatively small and newly formed "doors" presents the possibility of snagging of the airbag which could thereby destroy its ability to function as a life saving element. Patent US 4941678 (on which the pre-characterising part of claim 1 is based) describes a cover for an airbag module which has a central tear seam and a spline extending along each of two opposed sides of the cover. Each of the splines is snapped into an associated channel on an exterior surface of the module housing. A further airbag module is described in DE-U-9209125.3 in which a cover has side walls which extend down into and are secured to a module housing. A lid part of the cover is connected to one side wall by an integral hinge and to an opposed side wall by a latching channel on the cover engaging a latching spline on the opposed side wall. The lid part may alternatively comprise two doors each joined to a cover side wall by an integral hinge portion and snap-engaged with each other. Accordingly it is a primary object of the present invention to provide a cushion cover for a passenger side airbag module which does not require the use of fasteners or adhesives. Another object is to provide such a cover which is unperforated and thereby resistant to inadvertent splitting. Another object of the present invention is to provide such a cover which provides a relatively wide guide flap against which the airbag may deploy to reduce the possibilty of snags. Other objects, features, and advantages will become apparent from the following description and appended claims. Thus according to the invention there is provided an automotive airbag module assembly including a trough-shaped reaction canister having first and second end plates and first and second sidewalls defining an open mouth, means for mounting an inflator within said canister, a folded airbag within said canister, and a cover substantially closing the open mouth of said canister wherein said cover is held to the reaction canister by a first spline constituting a locking spline carried by said cover which is retained in a first channel constituting a locking channel defined by said first sidewall adjacent the open mouth, and a second spline carried by said cover which is retained in a second channel defined by said second sidewall adjacent the open mouth, said cover being openable upon airbag deployment, characterised in that said locking spline is engageable with said locking channel solely by longitudinal insertion therein, said second channel constitutes a latching channel and said second spline constitutes a latching spline which is disengaged from said latching channel by the force of the expanding airbag. The invention will now be described by way of example only with reference to the accompanying Figures in which: FIG. 1 is an end view of an airbag module assembly in accordance with this invention with one end plate partially broken away to illustrate its internal construction; and FIG. 2 is an exploded isometric view of the assembly of this invention with the end plates omitted, illustrating the relationship of the components. Figs. 1 and 2 illustrate a passenger side airbag module comprising a reaction canister 10 which may be extruded from a material such as aluminium. The reaction canister 10 is trough-shaped and includes spaced, substantially parallel, sidewalls 12, 14 which extend upwardly from the sides of a semi-cylindrical inflator housing 16. The inflator housing 16 serves to close the bottom of the trough-shaped reaction canister 10. The extruded reaction canister 10 includes conventional screw preparations 18 and mounting extensions 20 as required for the specific installation. The screw preparations 18 are conventional and serve to mount the end-plates 22, 24 which close the ends of the reaction canister 10. Housed within the inflator housing 16 is a conventional inflator 26 . The open top of inflator housing 16 is closed by a combination cushion retainer and diffuser plate 28 . The diffuser plate 28 defines a plurality of gas inlet openings 30 . The gas inlet openings 30 cause the gas from inflator 26 to be diffused into the open mouth of a folded airbag 32 housed within the reaction canister 10 . The diffuser plate 28 is retained within a pair of channels 34 (one being illustrated in FIG. 1 ) and opposed edges of the airbag mouth are retained within the same channels by means of rods 36 . None of the features so far described constitute the present invention and accordingly will not be described in more detail. In accordance with the present invention, the upper edge of the sidewall 12 of reaction canister 10 defines a locking channel 38 . The locking channel 38 is characterized by a relatively large square cross-section and a longitudinal slot 40 which extends along the length of the reaction canister 10 . The opposite sidewall 14 of the reaction canister 10 defines a semi-cylindrical latching channel 42 which also includes a longitudinal slot 44 running the length of the reaction canister 10 . The top of the reaction canister 10 is closed by a plastic cushion cover 46 which is substantially planar and rectangular and is characterized by a lack of perforations or tear lines. One of the major edges of the cushion cover 46 is formed with a spline 48 which has a substantially square cross-section to fit within the locking channel 38 . The spline 48 depends from a flange 50 on the cushion cover 46 . The thinness of the flange 50 allows it to pass through the slot 40 in locking channel 38 . The opposite longitudinal edge of the cushion cover 46 also carries a depending flange 52 which terminates in an enlarged bead-like (in cross section) spline 54 . The sizes of the flange 52 and the spline 54 are such that the spline may make a snap-fit engagement through the slot 44 of latching channel 42 whereby the spline 54 is housed within the latching channel 42 while the flange 52 rests within the slot 44 . The cushion cover 46 of this invention is installed on the reaction canister 10 after the installation of the folded airbag 32 . The spline 48 is inserted into the end of the locking channel 38 with the flange 50 extending through the slot 40 . No more than one of the endplates 22 , 24 has been installed at this juncture. The cushion cover 46 slides along the length of the reaction canister 10 and thereafter the opposite edge of the cover is pushed downward, causing the spline 54 to enter into a snap-fit engagement with the latching channel 42 . Alternatively, of course, the spline 54 could be inserted into the end of the latching channel 42 in the same manner as the spline 48 is inserted into the locking channel 38 . The completed assembly may be mounted in the vehicle with the cushion cover 46 mounted behind the breakaway dashboard portion. Alternatively, the cushion cover 46 may itself form a portion of the dashboard. In any event, when the unit is actuated, the airbag 32 begins to expand. The force of the expansion causes the spline 54 to disengage from the latching channel 42 allowing the cushion cover 46 to swing open in a counterclockwise rotation as viewed in FIG. 1 and as illustrated by the arrow. As the cushion cover 46 opens, it forms a guide flap against which the airbag 32 may deploy, thereby reducing the possibility of snags. It is believed that the many advantages of this invention will now be apparent to those skilled in the art. It will also be apparent that a number of modifications may be made therein without departing from its spirit and scope. For example, the locking channel 38 and the spline 48 are described as being of square cross section. However, it is only required that they be so configured as to form a relatively permanent engagement which resists separation by the force of the expanding airbag. Accordingly, the foregoing description is to be construed as illustrative only rather than limiting. This invention is limited only by the scope of the following claims.

Claims: An automotive airbag module assembly including a trough-shaped reaction canister (10) having first and second end plates (22, 24) and first and second sidewalls (12, 14) defining an open mouth, means for mounting an inflator (26) within said canister (10), a folded airbag (32) within said canister (10), and a cover (46) substantially closing the open mouth of said canister (10) wherein said cover is held to the reaction canister by: a first spline constituting a locking spline (48) carried by said cover (46) which is retained in a first channel constituting a locking channel (38) defined by said first sidewall adjacent the open mouth, and a second spline (54) carried by said cover (46) which is retained in a second channel (42) defined by said second sidewall adjacent the open mouth, said cover being openable upon airbag deployment, characterised in that: said locking spline (48) is engageable with said locking channel (38) solely by longitudinal insertion therein; said second channel constitutes a latching channel (42); and said second spline constitutes a latching spline (54) which is disengaged from said latching channel (42) by the force of the expanding airbag. The assembly according to claim 1 wherein said latching spline (54) is in snap-fit engagement with said latching channel (42). A method of assembly the airbag module assembly according to claim 1 or 2 including the steps of: longitudinally inserting said locking spline (48) into said locking channel (38); and then snap-fitting said latching spline (54) into said latching channel (42). A method of assembling the airbag module assembly according to claim 1 or 2 including the step of simultaneously longitudinally inserting said locking and latching splines (48, 54) respectively into said locking and latching channels (38, 42).

Inventors: GREEN DAVID J, MATZL BRYAN D, PAXTON DONALD J, GREEN, DAVID J., MATZL, BRYAN D., PAXTON, DONALD J.
Applicants: AUTOLIV ASP INC, AUTOLIV ASP, INC. (AN INDIANA CORP.)
Application year: 1994
Main classification: B60R21
IPC codes: B60R21